EARNINGS PER SHARE - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator for basic and diluted earnings per share:
Net income	$ 54,910	$ 29,023	$ 11,572	$ 36,369	$ 36,244	$ 976	$ 95,505	$ 73,589
Denominator:
Basic shares outstanding (in shares)	55,592			55,850			55,646	55,858
Dilutive effect of outstanding stock awards (in shares)	146			315			186	251
Dilutive shares outstanding (in shares)	55,738			56,165			55,832	56,109
Basic earnings per share (in USD per share)	$ 0.99			$ 0.65			$ 1.72	$ 1.32
Diluted earnings per share (in USD per share)	$ 0.99			$ 0.65			$ 1.71	$ 1.31